External shoe brake particularly for spinning and twisting spindles

ABSTRACT

In a friction brake that includes a manually operable pivotable brake lever to draw towards one another two brake shoes for engaging an interposed spindle to be braked, the work face of the brake lever engaging one of the brake shoes has a contour which has a flat portion and a convex portion spaced therefrom. If the lever is moved in one direction from its normal (released) position, a cooperation between said flat portion and a brake shoe will maintain the lever in its braking position even without continuing application of manual force. If the lever is moved in another direction from its normal position, a cooperation between said convex portion and said brake shoe will continuously urge said lever from its braking position into its normal position.

United States Patent 11 1 1111 3,731,768 Fetzer 1 May 8, 1973 [54]EXTERNAL SHOE BRAKE 3,297,112 1/1967 Mulholland et al. ..188/75PARTICULARLY FOR SPINNING AND 3,292,742 12/1966 Thomas ..188/75 XTWISTING SPINDLES FOREIGN PATENTS OR APPLICATIONS V [75] Inventor:Gustav Fetzer, 7344 Gingen, Germany 1,213,479 8/1958 France ..188/75[73] Assignee: Firma Zinser-Textilmaschinen p f Examine, Edw-ard A srokaGescuscha mit beschranktel' Assistant Examiner-W. Scott Carson tung,Postfach, Ebersbach, Ger- A,tmey Edwin Greigg many [22] Filed: Apr. 13,1971 ABSTRACT [21] A l N 133,559 In a friction brake that includes amanually operable pivotable brake lever to draw towards one another twobrake shoes for engaging an interposed spindle to [30] Forelgn ApphcauonPnonty Data be braked, the work face of the brake lever engaging Dec. 5,1970 Germany ..G 70 44 944.4 on of the brake shoes has a contour whichhas a flat portion and a convex portion spaced therefrom. If the [52][1.8. CI ..188/75 lever is moved in one direction from its normal [51]Int. Cl ..Fl6d 49/16 (released) position, a cooperation between saidfiat [58] Field of Search .74/104, 107; 188/75 portion and a brake shoewill maintain the lever in its braking position even without continuingapplication [56] R f r s Cit d of manual force. If the lever is moved inanother UNITED STATES PATENTS d1rect1on from its normal position, acooperatlon between sald convex portion and. said brake shoe W111297,089 4/1884 Rutherford .l88/75 X continuously urge said lever fromits braking position 2,660,395 11/1953 Mair et a1. ..74/107 X into itsnormal position. 1,778,570 1(1/1930 Soresi ..188/75 X 2,333,047 /1943Schlums ..188/75 X 10 Claims, 2 Drawing Figures 28 I 19 I I? 18 18 13 1"j' =3 C 1 1 1" L4 r l 21* j 1 1 V 32 I 36 21 2 11 l 1 a i l I. 1 e iEXTERNAL SHOE BRAKE PARTICULARLY FOR SPINNING AND TWISTING SPINDLESBACKGROUND OF THE INVENTION This invention relates to an external shoebrake particularly for spinning and twisting spindles and is of the typewhich has two brake shoes movable within limits and which, with the aidof a swingable lever, may be brought into a braking position against theforce of spring means and which, upon swinging the lever in an oppositedirection from said braking position, return into their releasedposition.

Brake structures of the aforeoutlined type are associated withindividual spindles in textile machines for the purpose of immobilizingby friction the associated spindle to permit maintenance, repair, orother work (i.e. upon yarn breakage) to be performed while other,unaffected spindles continue their rotation. The lever causing theimmobilization of the spindle may be actuated by the operators hand orknee.

It is a desideratum that the operating person be able to actuate thelever selectively in such a manner that either there appears a brakingaction which lasts only as long as the operating person holds the leverin the braking position and as soon as the lever is released, the brakereturns into its released position, or there is obtained a brakingaction which continues even after the operating person removes his handor knee from the lever. In the latter case the operating person then hasto exert a force to the lever to move it into the released position ifthe braking action is to be terminated.

OBJECT AND SUMMARY OF THE INVENTION It is an object of the invention toprovide an improved external shoe brake of simple and operationally safestructure which is adjustable by simple means and in which the brakelever may selectively be brought into either a stable braking positionwhich is maintained without continuous force exerted on the brake lever,or into an unstable braking position from which it is released as soonas the force exerted on the operating lever is removed.

Briefly stated, according to the invention, in an external shoe brake ofthe aforenoted type, the first brake shoe supports a tie rod mechanismwhich carries the operating lever. The latter has a contour face whichcooperates with an external surface of the second brake shoe forpressing both brake shoes against a rotationally symmetrical brakingface of the spindle. The contour face of the lever is designed in such amanner that if the lever is swung from its normal position in which thebrake shoes are disengaged from the spindle, in one direction, it is, byitself, retained in the braking position, whereas if swung in the otherdirection, it will stay in the braking position only as long as anexternal force is exerted to the lever in that direction.

The invention will be better understood, as well as further objects andadvantages will become more apparent, from the ensuing detailedspecification of a preferred, although exemplary, embodiment of theinvention taken in conjunction with the drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a partially sectional topplan view of the brake according to the preferred embodiment; and

FIG. 2 is a partially sectional side elevational view of the sameembodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENT Turning now to FIG. 1, there :isshown in dash-dot lines the circumference of the rotationallysymmetrical friction face 10 of a spindle with which the brake now to bedescribed is associated, The friction face 10 may be provided on thespindle in a conventional manner and is in general formed as the outerface of a bellshaped extension of the spindle whorl. Such a frictionface arrangement is well known and is therefore not dealt with in moredetail.

The bearing sleeve 11 supporting the spindle is affixed to a spindlerail 12 (FIG. 2). In the flange of the bearing sleeve 11 engaging thering rail 12 there are threadedly tightened at diametrically opposedlocations two bearing pins 13 which are in axial alignment with respectto one another. Each bearing pin 13 comprises a prismatic shank 14serving for the support and linear guidance of the first and secondbrake shoes 16 and 17, respectively, and a head 15 which serves as anabutment for determining the outermost position of the associated brakeshoe.

The brake shoes, 16, 17 are mirror images of one another and comprisebrake linings 18 at their faces adjacent the friction face 10 of thespindle. In addition to the two brake shoes l6, 17, the external shoebrake further comprises a tie rod assembly 19 which has two parallellinear bars 20 each carrying at one end a threadedly engaged nut 21. Thebars 20 are provided at their other ends with eyes 22 which have alignedbores for supporting a transverse connecting rod 23. The latter isrotatable, but is prevented from axial displacement. To the middle ofthe connecting rod 23 there is affixed a lever 24 which serves formanually operating the brake. The cylindrical shanks 25 of the two bars20 are disposed at a distance from the friction face 10 disposedtherebetween and are longitudinally displaceably supported incylindrical bearing bores of the two brake shoes.

- The nuts 21 serve to displace the first brake shoe 16 towards thefriction face 10 and further serve for setting the magnitude of thebraking force in the stable position 34 of the lever 24. Between eachnut 21 and an adjacent portion of the first brake shoe 16 there isprovided an elastic disc 29. Between the two brake shoes 16 and 17 eachbar 20 is surrounded by a biased compression spring 30 whichcontinuously urges the two.

brake shoes 16, 17 into positions in which they are dis engaged from thebrake face 10 of the spindle. The outermost positions of the brake shoesl6, 17 are determined by the heads 15 of the two bearing pins 13 servingas abutments. By rotating the bearing pins 13, the axial position of theabutments 15 may be set in a desired manner.

The lever 24 comprises a handle portion 31 and is, at its circumferenceadjacent the connecting rod 23, provided with a contour face 32 whichcooperates with a central, planar face portion 28 of the outer face ofthe second brake shoe 17. The contour face 32 is designed in such amanner that the lever 24, when swung in the direction of arrow A fromits normal position 33 shown in full lines in which the brake shoes l6,17 are disengaged from the brake face of the spindle, maintains itselfin the dash-dotted braking position 34, whereas if the lever is swungfrom its normal position in the other direction as indicated by arrow B,the lever will not be maintained by itself in the braking position. Thelever has to be maintained in this last-named braking position which isshown in dash-dot lines and indicated at 35, by continuously applying amanual force thereto. As soon as said force is removed, the leverreturns from the braking position 35 to its normal, released position33.

The stable or self-maintaining position of lever 24 in the brakingposition 34 is achieved by means of a flattened zone 36 which is part ofthe contour face 32 and which is disposed substantially parallel to thepivotal axis of the lever 24. The flattened zone 36 lies flat againstthe planar outer face 28 of the second brake shoe 17 in the brakingposition 34. Thus, in this position, the lever may be released withoutthereby changing the braking position. In order to release the brakewhen in braking position 34, the lever 24 has to be manually broughtback into its normal or released position 33.

By virtue of the elastic disc 29, the assembly comprising the brakeshoes 16, 17 and the tie rod assembly 19, has a small elasticity, sothat when the brake shoes 16, 17 lie against the friction face 10 of thespindle, the lever 24 may be brought into its stable braking position 34under the elastic deformation of the two discs 29. These elasticintermediate members 29 diminish the operating force necessary formoving the lever to and from the self-maintaining position 34 and,accordingly, also decrease the magnitude of the maximum pressure forceexerted by the brake shoes on the friction face 10 of the spindle duringthe movement of the lever 24 into the position 34. During the last-namedmovement there is encountered an unstable dead center in which the brakeshoes are compressed by the lever to a greater extent than when in theirover-the-center stable position 34. The elastic discs facilitate theovercoming of the unstable dead center and also prevent an excessiveload on the brake.

The unstable braking position 35 of the brake lever 24 is achieved bymeans of a convex curved zone 37 which is part of the contour face 32.The convex 'zone 37 is so situated with respect to the pivotal axis oflever 24 that in position 35 i.e. when the convex zone 37 engages theplanar portion 28 the springs 30 and the resilient discs 29 apply atorque to lever 24 in the direction of the inoperative position 33.Thus, an external (e.g. manual) force is needed to overcome said torquefor maintaining the lever 24 in its unstable braking position 35.

As it may be seen in FIG. 2, the contour face 32 of the lever 24 has, inaddition to the flattened zone 36 and the convex zone 37, a furtherflattened zone 38 which is parallel to the pivotal axis of the lever 24and which, dependent upon the setting of the nuts 21, lies or may lieagainst the planar outer face 28 of the second brake shoe 17 in thenormal or released position 33 of the lever 24. In this manner it isachieved that the normal position 33 is also a stable position of thelever 24.

Since the tie rod assembly 19, as well as the lever 24, is carriedexclusively by the two brake shoes 16, 17,

there appears a floating support of the brake assembly at all times onthe bearing pins 13 when the lever 24 is swung into a position in whichat least one of the brake shoes no longer lies against its associatedabutment head 15. In such an event the brake assembly as a whole may beshifted on the bearing pins 13 to and fro to an extent determined by theprevailing clearance. In this manner a self-centering of the brakeoccurs, so that the two brake shoes l6, 17 are, during braking,automatically pressed against the friction face 10 of the spindle withforces of identical magnitude. There is thus obtained a uniform andsecure braking effect which does not cause stresses in the spindlesupport.

In the embodiment shown and described, the pivotal axis of the lever ishorizontal which is particularly advantageous for a manual operation. Ifdesired, howi ever, the lever 24 with suitable means for connecting itto the transversal rod 23 may be arranged to swing about a verticalaxis. Such arrangement is particularly advantageous for an operation byknee.

It is an advantage of the brake according to the invention that thebraking force applied in the self-maintaining position 34 may be set oradjusted in a simple manner by means of the nuts 21. It is to beunderstood that instead of nuts 21, other means may be used foradjusting the brake force which may be associated, for example with thetie rod assembly 19.

In the above-described preferred embodiment the movement of the brakeshoes is linear. It is to be understood, however, that the brake shoesmay be so designed that they are pivotally held at one end and cooperatewith a tie rod assembly at the other end. A floating support of the typereferred to hereinabove is possible by affixing the pivot pins of thebrake shoes to a movable member, the motion of which is limited to alinear displacement tangentially with respect to the spindle.

That which is claimed is:

1. In a brake for frictionally engaging a rotationally symmetrical faceof a rotary member, the improvement comprising A. a first brake shoemovable towards and away from said rotary member,

B. a second brake shoe movable towards and away from said rotary memberand having an outer flat face portion,

C. a tie rod assembly connecting said first and second brake shoes toone another and including 1. two bars arranged symmetrically withrespect to an axial plane of said rotary member,

2. a transversal rod connecting said bars with one another,

D. a brake lever pivotally held on said transversal rod adjacent saidouter flat face portion of said second brake shoe; said brake leveradapted to assume a first position in which said brake is in a releasedcondition and arbitrarily chosen second and third positions in whichsaid brake is in an actuated position; said brake lever having 1. ahandle portion for receiving an external force applying a torque to saidbrake lever,

2. a contour face for engaging said outer flat face portion of saidsecond brake shoe to cause displacement of said brake shoes with respectto one another and said rotary member; said contour face having a. afirst zone engaging said outer flat face portion of said second brakeshoe in said second position; the engagement between said first zone andsaid outer flat face portion maintaining said brake in said secondposition in the absence of an external force and b. a second zoneengaging said outer flat face portion of said second brake shoe in saidthird position; the engagement between said second zone and said outerflat face portion causing said brake lever to move into said firstposition in the absence of an external force and E. two alignedstationary bearing pins disposed diametrically opposite with respect tosaid rotary member, said bearing pins supporting and guiding said brakeshoes in their movement in a linear path.

2. An improvement as defined in claim 1, wherein said first zone of saidcontour face is flat and having a plane substantially parallel to thepivotal axis of said brake lever.

3. An improvement as defined in claim 1, including elastic meansdisposed between said tie rod assembly and one of said brake shoes; saidelastic means yields by means of elastic deformation when said brakeshoes engage said rotary member and said brake lever is moved into saidsecond position.

4. An improvement as defined in claim 3, wherein said elastic means isconstituted by at least one elastic disc disposed between at least oneof said bars and said first brake shoe.

5. An improvement as defined in claim 1, wherein each brake shoeincludes two throughgoing guide bores; each bar passes through one guidebore in the first brake shoe and through one guide bore in the secondbrake shoe.

6. An improvement as defined in claim 1, including at least onecompression spring disposed between said brake shoes and being inengagement therewith; said compression spring urges said brake shoesaway from one another and from said rotary member.

7. An improvement as defined in claim 1, wherein said second zone ofsaid contour face is outwardly convex.

8. An improvement as defined in claim 1, wherein said contour faceincludes a third zone of flat configuration having a plane substantiallyparallel to the pivotal axis of said brake lever and adapted to engagesaid outer flat face portion of said second brake shoe in said firstposition of said brake lever.

9. An improvement as defined in claim 1, including means for adjustingthe braking force of said brake exerted to said rotary member in saidsecond position of said brake lever.

10. In a brake for frictionally engaging a rotationally symmetrical faceof a rotary member, the improvement comprising A. a first brake shoemovable towards and away from said rotary member, I

B. a second brake shoe movable towards and away from said rotary memberand having an outer flat face portion,

C. a tie rod assembly connecting said first and second brake shoes toone another,

D. a brake lever pivotally held on said tie rod assembl adjacent saidouter flat face portion of said secon brake shoe; said brake leveradapted to assume a first position in which said brake is in a releasedcondition and arbitrarily chosen second and third positions in whichsaid brake is in an actuated position; said brake lever having 1. ahandle portion for receiving an external force applying a torque to saidbrake lever,

2. a contour face for engaging said outer flat face portion of saidsecond brake shoe to cause displacement of said brake shoes with respectto one another and said rotary member; said contour face having a. afirst zone engaging said outer flat face portion of said second brakeshoe in said second position; the engagement between said first zone andsaid outer flat face portion maintaining said brake in said secondposition in the absence of an external force,

b. a second zone engaging said outer flat face portion of said secondbrake shoe in said third position; the engagement between said secondzone and said outer flat face portion causing said brake lever to moveinto said first position in the absence of an external force,

E. a bearing member for supporting said rotary member,

F. at least two bearing pins affixed to said bearing member forsupporting and guiding said brake shoes in their radial displacementwith respect to said rotary member and G. an abutment forming part ofeach bearing pin to determine the outermost location of said brake shoesin the first position of said brake, lever.

1. In a brake for frictionally engaging a rotationally symmetrical faceof a rotary member, the improvement comprising A. a first brake shoemovable towards and away from said rotary member, B. a second brake shoemovable towards and away from said rotary member and having an outerflat face portion, C. a tie rod assembly connecting said first andsecond brake shoes to one another and including
 1. two bars arrangedsymmetrically with respect to an axial plane of said rotary member,
 2. atransversal rod connecting said bars with one another, D. a brake leverpivotally held on said transversal rod adjacent said outer flat faceportion of said second brake shoe; said brake lever adapted to assume afirst position in which said brake is in a released condition andarbitrarily chosen second and third positions in which said brake is inan actuated position; said brake lever having
 1. a handle portion forreceiving an external force applying a torque to said brake lever,
 2. acontour face for engaging said outer flat face portion of said secondbrake shoe to cause displacement of said brake shoes with respect to oneanother and said rotary member; said contour face having a. a first zoneengaging said outer flat face portion of said second brake shoe in saidsecond position; the engagement between said first zone and said outerflat face portion maintaining said brake in said second position in theabsence of an external force and b. a second zone engaging said outerflat face portion of said second brake shoe in said third position; theengagement between said second zone and said outer flat face portioncausing said brake lever to move into said first position in the absenceof an external force and E. two aligned stationary bearing pins disposeddiametrically opposite with respect to said rotary member, said bearingpins supporting and guiding said brake shoes in their movement in alinear path.
 2. An improvement as defined in claim 1, wherein said firstzone of said contour face is flat and having a plane substantiallyparallel to the pivotal axis of said brake lever.
 2. a contour face forengaging said outer flat face portion of said second brake shoe to causedisplacement of said brake shoes with respect to one another and saidrotary member; said contour face having a. a first zone engaging saidouter flat face portion of said second brake shoe in said secondposition; the engagement between said first zone and said outer flatface portion maintaining said brake in said second position in theabsence of an external force and b. a second zone engaging said outerflat face portion of said second brake shoe in said third position; theengagement between said second zone and said outer flat face portioncausing said brake lever to move into said first position in the absenceof an external force and E. two aligned stationary bearing pins disposeddiametrically opposite with respect to said rotary member, said bearingpins supporting and guiding said brake shoes in their movement in alinear path.
 2. a transversal rod connecting said bars with one another,D. a brake lever pivotally held on said transversal rod adjacent saidouter flat face portion of said second brake shoe; said brake leveradapted to assume a first position in which said brake is in a releasedcondition and arbitrarily chosen second and third positions in whichsaid brake is in an actuated position; said brake lever having
 2. acontour face for engaging said outer flat face portion of said secondbrake shoe to cause displacement of said brake shoes with respect to oneanother and said rotary member; said contour face having a. a first zoneengaging said outer flat face portion of said second brake shoe in saidsecond position; the engagement between said first zone and said outerflat face portion maintaining said brake in said second position in theabsence of an external force, b. a second zone engaging said outer flatface portion of said second brake shoe in said third position; theengagement between said second zone and said outer flat face portioncausing said brake lever to move into said first position in the absenceof an external force, E. a bearing member for supporting said rotarymember, F. at least two bearing pins affixed to said bearing member forsupporting and guiding said brake shoes in their radial displacementwith respect to said rotary member and G. an abutment forming part ofeach bearing pin to determine the outermost location of said brake shoesin the first position of said brake lever.
 3. An improvement as definedin claim 1, including elastic means disposed between said tie rodassembly and one of said brake shoes; said elastic means yields by meansof elastic deformation when said brake shoes engage said rotary memberand said brake lever is moved into said second position.
 4. Animprovement as defined in claim 3, wherein said elastic means isconstituted by at least one elastic disc disposed between at least oneof said bars and said first brake shoe.
 5. An improvement as defined inclaim 1, wherein each brake shoe includes two throughgoing guide bores;each bar passes through oNe guide bore in the first brake shoe andthrough one guide bore in the second brake shoe.
 6. An improvement asdefined in claim 1, including at least one compression spring disposedbetween said brake shoes and being in engagement therewith; saidcompression spring urges said brake shoes away from one another and fromsaid rotary member.
 7. An improvement as defined in claim 1, whereinsaid second zone of said contour face is outwardly convex.
 8. Animprovement as defined in claim 1, wherein said contour face includes athird zone of flat configuration having a plane substantially parallelto the pivotal axis of said brake lever and adapted to engage said outerflat face portion of said second brake shoe in said first position ofsaid brake lever.
 9. An improvement as defined in claim 1, includingmeans for adjusting the braking force of said brake exerted to saidrotary member in said second position of said brake lever.
 10. In abrake for frictionally engaging a rotationally symmetrical face of arotary member, the improvement comprising A. a first brake shoe movabletowards and away from said rotary member, B. a second brake shoe movabletowards and away from said rotary member and having an outer flat faceportion, C. a tie rod assembly connecting said first and second brakeshoes to one another, D. a brake lever pivotally held on said tie rodassembly adjacent said outer flat face portion of said second brakeshoe; said brake lever adapted to assume a first position in which saidbrake is in a released condition and arbitrarily chosen second and thirdpositions in which said brake is in an actuated position; said brakelever having